Aerofoil-shaped fluid-cooled blade for a fluid flow machine



Nov. 21, 1967 A BILL ETAL AEROFOIL-SHAPED FLUID-COOLED BLADE FOR A FLUID FLOW MACHINE Filed Nov. 19, 1965 /7 l8 lo l6 '/2 Attorneys lnvenlorg Z W 5 United States Patent Ofiice 3,3533% Patented Nov. 21, 1967 3,353,351 AEROFOIL-SHAPED FLUlD-CGGLED BLADE FQR A FLUID FLOW MACHINE Arthur Bill, Derby, Thomas Steel, Littleover, and Michael Poucher, Allestree, England, assignors to Rolls-Royce Limited, Derbyshire, England, a British company Filed Nov. 19, 1965, Ser. No. 508,683 Claims priority, application Great Britain, Dec. 2, 1964, 49,101/64 11 Claims. (Cl. tie-39.65)

ABSTRACT F THE DISCLOSURE A hollow aerofoil-shaped blade for use, for example, as a flame tube-mounted guide vane in a gas turbine engine, the blade having an internal hollow sleeve which is spaced from the blade wall. The sleeve is provided with cooling air outlets for directing some of the cooling fluid supplied to the interior thereof to the space between the sleeve and the blade wall, this fluid subsequently escaping to the exterior of the blade, and is further provided with passages which provide direct communication between the sleeve and the blade wall so that the remainder of the fluid supplied to the sleeve may pass to the exterior of the blade without mixing with fluid in the intervening space.

The present invention relates to an aerofoil-shaped blade of type adapted for use in a fluid-flow machine such as a gas turbine engine or a steam turbine.

It is known to cool such blades by the use of cooling fluid and the object of the invention is to provide a blade in which such cooling is particularly effective.

According to the invention, there is provided an aerofoil-shaped blade adapted for use in a fluid flow machine, said blade having an external wall, characterised by fluid receiving means surrounded by and spaced from said wall for receiving cooling fluid and directing some of the cooling fluid over the interior of said wall for cooling said wall, said wall having apertures enabling the cooling fluid to escape from the space between said fluid receiving means and said wall, and means defining a passage wherein a portion of the cooling fluid entering the fluid receiving means passes across the said space directly to the exterior of the said blade without mixing with the fluid in the space.

The fluid receiving means may comprise a hollow sleeve having apertures for directing said cooling fluid towards a part of said wall which tends to be relatively hot during operation of the engine, and towards the trailing edge of said blade, said wall having apertures in said trailing edge enabling said cooling fluid to escape from the said space.

Preferably, there are provided one or more partitions which divide the hollow sleeve into one or more first portions having apertures for directing said cooling fluid into the said space and one or more second portions from which fluid may pass directly from the sleeve to the exterior of the blade through said passage defining means.

The said one or more partitions are preferably provided with extensions which project from the sleeve and which are adapted to be disposed in a stream of the fluid for directing fluid from the stream into the sleeve.

Preferably there are more than one passage-defining means and means are provided for ensuring a substantially even distribution of air entering said second portion or portions and passing therefrom to the passage-defining means. Thus there may be one or more deflectors each of which projects from the sleeve and which is adapted to be disposed in a stream of the fluid for directing fluid from the stream into a respective second portion of the sleeve.

The blade according to the invention may also be provided with spaced-apart flat strips on the leading edge thereof which form with the blade a channel for deflecting a portion of the fluid, which in operation will pass along a path exteriorly of the blade generally from the leading edge to the trailing edge thereof. a fluid-flow machine, such as a gas turbine engine, having an inlet at one end for primary combustion air, means for dispersing fuel in said primary combustion air and an outlet at the other end for the combustion gases, and an aerofoil-shaped blade as previously described disposed in said combustion chamber between the inlet and outlet for guiding said combustion gases to said outlet and arranged so that the air from the passage-defining means fOXIILv the secondary combustion air.

The invention further provides a fluid-flow machine, such as a gas turbine engine comprising one or more aerofoil-shaped blades as previously described.

A preferred embodiment of the invention will now be described, by way of example only, and with reference to the accompanying drawings, in which:

FIGURE 1 is a sectional view of part of a gas turbine engine having aerofoil-shaped blades in accordance with the present invention,

FIGURE 2 is a perspective cut-away view of the combustion chamber of part of the gas turbine engine of FIGURE 1, and

FIGURE 3 is a perspective cut-away view of a blade in accordance with the invention.

In FIGURE 1 there is shown on one side of the centreline 10 of a gas turbine engine, an axial air compressor 11, a combustion chamber 12 and a power producing turbine 13. A pipe 14 is provided for the supply of fuel to the combustion chamber 12, the fuel being sprayed, in operation against a splash plate 15, and transversely dispersed from a curled end 16 of the splash plate 15 into the air stream from the compressor 11. It will be seen that the air delivered by compressor 11 is divided into a first air stream which enters the combustion chamber 12 at inlet 17 and a second air stream which proceeds in the general direction of arrow 18. The air-fuel mixture is ignited by suitable means (not shown) and the resulting combustion gases expand towards outlet 19 of the combustion chamber 12. i

It is desirable that the combustion gases impinge on the blades of the turbine 13 at an angle selected to give the turbine 13 maximum efliciency and to this end, aerofoilshaped blades or vanes 20 are provided which guide the combustion gases towards the turbine to impinge thereon generally at the selected angle. T 0 ensure that the temperature of the combustion gases is maintained sufliciently low to avoid damage to the downstream parts of the combustion chamber 12 and the turbine 13, it is preferred to admit cooling or dilution air to the combustion chamber immediately downstream of the zone of mixing of the primary air and fuel. It is also desirable that the blades 20 be cooled against the high temperatures resulting from combustion. The invention enables the blades 20 to be cooled by means of a portion of the second air stream, and accordingly the blades 20 are made hollow and the second air stream is directed into the blades 20 by means of scoops 21, 22 which project thereinto. The main part of the second air stream can leave the interior of each blade 20 through apertures 23, and the remainder after circulating within the blade 20 to cool it leaves through smaller apertures 25 at the trailing edge of blade 20.

In the illustrated embodiment, the apertures 23 are all disposed on one side only of blade 20 but the invention is not limited to this feature, and the apertures may be arranged on both sides if desired. To providefor thorough mixing of the primary air and fuel, the radially outer 2nd of the leading edge of blade 26 is provided with two apaced-apart strips 26 forming a channel with the leading edge such that a portion of the incoming primary air, which may be a major portion, is deflected radially inwardly transverse to the general flow path of the gases, whereby to promote mixing. The strips 26 in the illustrated embodiment are arranged generally parallel to each other but they may also be disposed to be non-parallel if this is found to provide the desired gas circulation. It will be seen by reference to FIGURE 2 that the combustion chamber 12 is, in this instance, of annular form and is divided into fairly distinct combustion regions by a number of angularly spaced-apart blades 20, the primary and secondary air-streams being divided from the compressor delivery stream alternately angularly around the annular outlet from the compressor 11. Each blade 20 is provided internally with a hollow sleeve 27 the open top portion of one of which can be seen in FIGURE 2 and more detail of which can be seen in FIG. 3. The radially inner portion of the sleeve 27 is sealed to the radially inner wall of combustion chamber 12. The scoop 21 forms an outwardly projecting extension of a partition which extends to the radially inner end of sleeve 27 thus dividing sleeve 27 into tWo chambers 23, 29, and the shape of the scoop 21 is such as to direct the air which strikes it into chamber 2%. Scoop 22 forms an outwardly projecting extension of a partition which extends only part way towards the radially inner end of sleeve 27, so that the air which strikes it can be directed into the radially outer part of compartment 29 to feed the radially outer ones of the apertures 23 through tubes 31, while the air which does not strike it enters the downstream portion of compartment 29 due to the termination of the second air passage and passes in a generally clockwise direction as shown in FIGURE 3 to the radially inner ones of apertures 23 through corresponding tubes 31.

Thus the air entering compartment 29 is distributed fairly evenly among the apertures 23. The main portion of the second air stream is directed into chamber 29 by scoop 22, and thus, without mixing with cooling air in the space between the sleeve 27 and the blade 20, passes directly out of sleeve 27 to the combustion chamber 12 through tubes 31, which terminate in the apertures 23 in the exterior wall 20a of blade 20. The tubes 31 also serve to support the sleeve 27 in its spaced-apart relationship to the wall 20a. The second air stream which gathers in compartment 28 of sleeve 27 is used for cooling the exterior wall 26a before passing to the combustion chamber 12. The leading edge of sleeve 27 is formed with apertures 32, so that cooling air can pass from chamber 28 to the space betwen the sleeve 27 and the leading edge of blade 2%), this leading edge tending to be the hottest part of blade 20 during the operation of the engine.

The cooling air will circulate from the leading edge sleeve apertures 32 around the sleeve 27, and this air after having helped to cool the wall 20a of the blade 20 by circulating in the space between the sleeve 27 and the wall 20a of the blade 20, and escapes from blade 20 via apertures 25.

It is to be understood that while apertures 25 and 32 have been depicted as slots in the drawings, they could equally well be any other suitable shape, such as circular. It is also to be understood that the invention is not limited to two scoops 21, 22 and two chambers 23, 29 but that any suitable number of scoops and chambers may be used. Further, Where the operational pressure conditions in the combustion chamber permit, it is possible that the leading edge regions of the wall 20a of the blade 20 could be apertures to allow the escape of some cooling air from the space between the sleeve 27 and the leading edge of blade 20, this air then passing as a film rearwardly over the external surface of blade 2% to protect the blade 20 against direct convection from the combustion gases.

In an embodiment (not illustrated) of a blade according to the invention incorporating this latter feature, the

spaced-apart strips 26 are joined to each other by a web to form a channel which is fixedly disposed slightly upstream of the leading edge of the blade, and the apertures for this film cooling air are formed in the wall 20a of blade 2! on the leading edge of blade 20 so that the air can pass between the leading edge and the channel.

We claim:

1. An aerofoil-shaped blade adapted for use in a fluid flow machine, said blade having an external wall and fluid receiving means surrounded by and spaced from said wall to define a space for receiving cooling fluid from the fluid receiving means and directing some of the cooling fluid over the interior of said Wall for cooling said wall, said Wall having apertures enabling the cooling fluid to escape from the space between said fluid receiving means and said wall, and means defining a passage wherein a portion of the cooling fluid entering the fluid receiving means passes across the said space directly to the exterior of the said blade without mixing with the fluid in the space.

2. A blade according to claim 1 in which the fluid receiving means comprises a hollow sleeve having apertures for directing said cooling fluid into said space towards a part of said wall which tends to be relatively hot during operation of the engine, and towards the trailing edge of the blade, said wall apertures being in the downstream portion of said blade.

3. A blade according to claim 2 in which there is provided at least one partition which divides the sleeve into a first portion including the apertures in said sleeve for directing said cooling fluid into said space, and at least one second portion from which fluid may pass directly from the sleeve to the exterior of the blade through said passage defining means.

4. A blade according to claim 3 in Which said partition is provided with an extension which projects from said sleeve and which is adapted to be disposed in a stream of the fluid for directing fluid from the stream into the sleeve.

5. A blade according to claim 2 in which there is provided a partition dividing the sleeve into tWo portions, said passage defining means being arranged for fluid to escape from the downstream one of the portions to the exterior of the blade, the part of the sleeve around the other portion containing said apertures for directing the cooling fluid into said space.

6. A blade according to claim 3 in which there are more than one passage defining means and means are provided for ensuring a substantially even distribution of air entering said second portion and passing therefrom to each passage defining means.

7. A blade according to claim 6 in which there is at least one deflector which projects from the sleeve and which is adapted to be disposed in the stream of the fluid for directing fluid from the stream into a respective second portion of the sleeve.

8. A blade according to claim 2 in which means are provided for permitting the cooling fluid to circulate in said space from a region adjacent the upstream edge of said blade to the apertures in the downstream edge of the external wall.

9. A blade according to claim 1 in which the passage defining means serves to support the fluid receiving means in fixed spaced relation to said external wall.

10. A blade according to claim 1 in which the upstream edge thereof is provided with spaced apart flat strips which form with the blade 2. channel for deflecting a portion of the fluid, which portion passes along a path exteriorly of the blade generally from the upstream leading edge to the downstream edge thereof.

11. A combustion chamber for a fluid flow machine having an inlet at one end for primary combustion air,

References Cited UNITED STATES PATENTS 8/1958 Petrie et a1. 25339 3/1966 Clarke et a1. 60-39.

JULIUS E. WEST, Primary Examiner. 

1. AN AEROFOIL-SHAPED BLADE ADAPTED FOR USE IN A FLUID FLOW MACHINE, SAID BLADE HAVING AN EXTERNAL WALL AND FLUID RECEIVING MEANS SURROUNDED BY AND SPACED FROM SAID WALL TO DEFINE A SPACE FOR RECEIVING COOLING FLUID FROM THE FLUID RECEIVING MEANS AND DIRECTING SOME OF THE COOLING FLUID OVER THE INTERIOR OF SAID WALL FOR COOLING SAID WALL, SAID WALL HAVING APERTURES ENABLING THE COOLING FLUID TO ESCAPE FROM THE SPACE BETWEEN SAID FLUID RECEIVING MEANS AND SAID WALL, SAID MEANS DEFINING A PASSAGE WHEREIN A PORTION OF THE COOLING FLUID ENTERING THE FLUID RECEIVING MEANS PASSES ACROSS THE SAID SPACE DIRECTLY TO THE EX- 